From ce1ab7e1ce58f33a0dc6e7dc883cfd6710e899e3 Mon Sep 17 00:00:00 2001
From: Greg Ercolano <erco@seriss.com>
Date: Fri, 5 Sep 2014 02:59:00 +0000
Subject: Fixes to how new move() operations handle the concept of 'above' and
 'below' when referring to items instead of index positions.

Small offsets needed due to how the arrays are scrolled
after a move operation.



git-svn-id: file:///fltk/svn/fltk/branches/branch-1.3@10272 ea41ed52-d2ee-0310-a9c1-e6b18d33e121
---
 src/Fl_Tree_Item.cxx       |  5 ++++-
 src/Fl_Tree_Item_Array.cxx | 19 +++++++++----------
 2 files changed, 13 insertions(+), 11 deletions(-)

(limited to 'src')

diff --git a/src/Fl_Tree_Item.cxx b/src/Fl_Tree_Item.cxx
index a5ec92d27..8c68c2518 100644
--- a/src/Fl_Tree_Item.cxx
+++ b/src/Fl_Tree_Item.cxx
@@ -539,8 +539,11 @@ int Fl_Tree_Item::move(Fl_Tree_Item *item, int op, int pos) {
   }
   if ( !from_parent || !to_parent ) return -1;
   if ( from < 0 || to < 0 ) return -2;
-  if ( op == 1 ) to++;				// 'below'? apply +1 offset for 'to'
   if ( from_parent == to_parent ) {		// same parent?
+    switch (op) {				// 'to' offsets due to scroll
+      case 0: if ( from < to && to > 0 ) --to; break;
+      case 1: if ( from > to && to < to_parent->children() ) ++to; break;
+    }
     if ( from_parent->move(to, from) < 0 )	// simple move among siblings
       return -4;
   } else {					// different parent?
diff --git a/src/Fl_Tree_Item_Array.cxx b/src/Fl_Tree_Item_Array.cxx
index 2610bb2a6..7f7476569 100644
--- a/src/Fl_Tree_Item_Array.cxx
+++ b/src/Fl_Tree_Item_Array.cxx
@@ -234,6 +234,10 @@ void Fl_Tree_Item_Array::swap(int ax, int bx) {
 #endif /* FLTK_ABI_VERSION */
 
 /// Move item at 'from' to new position 'to' in the array.
+/// Due to how the moving an item shuffles the array around,
+/// a positional 'move' implies things that may not be obvious:
+/// - When 'from' moved lower in tree, appears BELOW item that was at 'to'.
+/// - When 'from' moved higher in tree, appears ABOVE item that was at 'to'.
 ///
 ///     \returns 0 on success, -1 on range error (e.g. if \p 'to' or \p 'from' out of range)
 ///
@@ -241,23 +245,18 @@ int Fl_Tree_Item_Array::move(int to, int from) {
   if ( from == to ) return 0;    // nop
   if ( to<0 || to>=_total || from<0 || from>=_total ) return -1;
   Fl_Tree_Item *item = _items[from];
-  Fl_Tree_Item *prev = item->prev_sibling();
-  Fl_Tree_Item *next = item->next_sibling();
   // Remove item..
   if ( from < to )
-    for ( int t=from; t<to && t<_total; t++ )
+    for ( int t=from; t<to && t<(_total+1); t++ )
       _items[t] = _items[t+1];
   else
-    for ( int t=from; t>to; t-- )
+    for ( int t=from; t>to && t>0; t-- )
       _items[t] = _items[t-1];
   // Move to new position
   _items[to] = item;
-  // Adjust for new siblings
-  _items[to]->update_prev_next(to);
-  _items[from]->update_prev_next(from);
-  // Adjust old siblings
-  if ( prev ) prev->update_prev_next(from-1);
-  if ( next ) next->update_prev_next(from);
+  // Update all children
+  for ( int r=0; r<_total; r++ )	// XXX: excessive to do all children,
+    _items[r]->update_prev_next(r);	// XXX: but avoids weird boundary issues
   return 0;
 }
 
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